A social housing tenant accused of stabbing his neighbour in a "brutal" two-on-one attack was lying when he said he acted in self-defence, a prosecutor has told a court.
Kobi Guarini, 31, is on trial in the ACT Supreme Court charged with one count of intentionally inflicting grievous bodily harm. He has pleaded not guilty to the charge.
In his closing statements on Thursday, prosecutor Anthony Williamson told jurors they should exercise their "common sense" in determining whether Mr Guarini was guilty.
Mr Williamson conceded Mr Guarini's alleged victim was behaving "irrationally and aggressively" when, on August 22, 2018, he confronted Mr Guarini at their Belconnen unit complex.
He said the alleged victim asked Mr Guarini for about $1000 - which he did not owe him - and refused him entry to his own apartment at Illawarra Court before punching him in the face.
Mr Guarini could have called the police then, Mr Williamson said, but instead, he went and fetched his mate and a knife.
Mr Guarini allegedly came back to Illawarra Court and stabbed his neighbour in the back and neck. He and his friend allegedly punched and kicked the man while he was on the ground.
"Is attacking someone whilst they're on the ground really consistent with someone acting in self-defence?" Mr Williamson asked jurors on Thursday.
"[It] amounts to a a gratuitous, unnecessary, and unreasonable use of violence."
Mr WIlliamson said during the attack, Mr Guarini's victim sustained lacerations - some of which went 80 per cent of the way through muscle - as well as nerve damage and permanent scarring.
He said one witness described the attack as turning "brutal" once it spilled out onto College Street.
Defence barrister Steven Whybrow said Mr Guarini got the "little" knife so he could scare his "delusional" and aggressive neighbour away if necessary and get back into his apartment.
"It's not Crocodile Dundee, 'that's a knife'," Mr Whybrow said.
He said professionals had assessed Mr Guarini's alleged victim as "a risk to his neighbours".
Mr Whybrow said there was no way Mr Guarini could have known his neighbour was still at the complex when he returned with the knife and he had no intention of stabbing him.
He said it was agreed that Illawarra Court was a "difficult" place to live "where you don't really call the cops", and "if you do, they don't turn up".
Mr Whybrow said Mr Guarini's alleged victim seemed to "get a pass" for everything he did and he basically attempted to rob Mr Guarini. He said the neighbour, who was holding "two big lumps of metal", charged at Mr Guarini when he returned to Illawarra Court
"The law does not require [Mr Guarini] to stand there and be beaten," Mr Whybrow said.
"He just wanted to say, 'get out of my way' ... and then things got taken out of hand [by his alleged victim]."
The jury will retire to deliberate.